The invention relates to a compound feed for lactating sows and a preparation method thereof. The invention discloses an complete compound feed for the lactating sows, comprising the following components: corns, bean pulp, imported fish meal, fermented cottonseed meal, imported dried porcine solules, alfalfa meal, rice bran, wheat bran, oil, calcium hydrophosphate, mountain meal, edible salt, compound microbial ecological agents like yeast and the like, choline chloride, a food calling agent, an acidulant, an amino acid additive, compound vitamins, organic compound trace elements and an auxiliary functional packet. The feed fully completely meets the nutrition requirements for postpartum lactation and postweaning estrus of the sows and can ensure that the sows provide more milk with high quality during lactation so that suckling pigs grow at high speed and has good weaning weight and small weaning stress; and the sows have less postpartum diseases, timely rut for hybridization after weaning, the non-breeding days of the sows are shortened, and the annual live piglet number and the utilization age limit of the sows and the like are increased.